Troubleshooting GM Door Lock Actuatorsby Don Bowman
GM door lock actuators are electromagnet actuators that work by reversing the polarity to the actuator. The actuators are a separate piece attached to the door latch assembly and act as an integral part of the assembly. Most of the locks on the late-model vehicles are remotely operated, as well as manually.
Testing the GM Door Lock Actuators
Start by trying the GM remote control door lock actuator. If it doesn't work, open the door with the key and try the door locks with the switch on the door. If the door locks work, split the case on the remote and replace the battery. If they still don't work, the remote is bad.
If the door locks work with the remote and not with the switch, the switch is defective. If they do not work at all, the door panel must be removed to inspect the door lock mechanism. Remove the two screws in the armrest. Remove the small, V-shaped piece that covers the attachment point of the outside mirror. Insert a standard screwdriver between the door panel and the door frame. Pry the male snaps that hold the door panel on from the female recesses in the door frame. There are usually three on each of the three sides. Just start at the bottom of the door and pop one snap out, slide the screwdriver to the next, and so on.
Lift up the door panel to release it at the top sill by the window, and move it toward the rear just enough to remove the door handle from the panel. Move it back toward you enough to remove the electrical connections. Remove the door panel and put it aside. Looking into the access hole in the door panel, look at the door latch from the inside. There are two rods that are attached to the door lock actuator. One of the rods can be seen running from the key door lock down to the actuator, and another from the actuator to the door latch. Make sure these rods are hooked up to the actuator and that the small plastic snaps that hold the rods on are in place. These are all easy to see, although a flashlight makes it easier.
If the rods are all on, go to the removed door panel and remove the window switch containing the door lock button. On some models the door lock switch is separate, so just remove it. Attach the switch to the connector on the door. Using a test light, check for power at the switch. If there is no power, check the fuses. If there is power, check the other terminal at the switch for power as the switch is moved to either up or down. It should have power at one terminal continuously, and at each of the other terminals when the switch is moved.
Replacing the GM Door Lock Actuators
If there is no power when the switch is in the up or down position, the switch is bad. If there is power, the door lock actuator is getting power and is defective. It's not surprising, because they fail often. The switch must be removed. Use a common screwdriver and push the plastic locks loose, holding the rods to the door latch mechanism as a whole. The will be two rods to the door lock and two rods from the door latch to the inside of the door--the long rods. The long rods must be removed from the door latch mechanism. Disconnect the electrical connector to the door latch mechanism. Use a large Phillips screwdriver and remove the three large screws on the outside back of the door that hold the door latch to the door frame. Remove the door latch from the door access hole. Remove the screws holding the black door lock mechanism to the door latch. Replace it with a new one and install all of the components in reverse order of removal.